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Fracture Modeling in Computer Graphics

Fracture Modeling in Computer Graphics. A survey. MIIACS Lien Muguercia Torres Advisors Dr. Gustavo A. Patow Dr. Carles Bosch. Introduction. Introduction. Introduction. Why fracture?. This thesis. Overview. Background Physically-based methods Non-physically based methods

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Fracture Modeling in Computer Graphics

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  1. Fracture Modeling in ComputerGraphics A survey MIIACS Lien Muguercia Torres Advisors Dr. Gustavo A. Patow Dr. Carles Bosch

  2. Introduction

  3. Introduction

  4. Introduction

  5. Why fracture? This thesis

  6. Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work

  7. Background

  8. Aging and weathering processes

  9. Aging and weathering processes [Merillou08]

  10. Aging and weathering processes • Specific aging model • Simulation • Global aging models • Aging as particles [Chen05] • Example based texture synthesis [Gu96; Matusik03]

  11. Cracks and fractures in nature • Cracks: long and tiny • Fractures: desattachments • Mechanic classifications

  12. Cracks and fractures in nature • Materials parameters • Stress • Strain • Yield strength • Fracture • Trans-granular • Inter-granular

  13. Simulation fracture • Common steps over time • Compute internal forces • Determinate location and orientation • Modify the model

  14. Physical models • Mass-spring system • Fast implementation/runtime • Poor visual results • FEM • Simulation precision • Computational cost • Mesh-less methods • Avoid mesh reconstruction • Bounding conditions

  15. Time integration • Compute the state by extrapolating the previous one • Solving the implicit methods • by linearization • Compute the state at the end of the time step

  16. Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work

  17. Physically-based methods

  18. Mass-spring models • Rigid bodies • Bodies as hybrid between rigid and deformable [Terzopoulos88; Norton91] • Model behavior of solid objects

  19. Mass-spring models • Rigid bodies • Bodies as hybrid between rigid and deformable [Terzopoulos88; Norton91] • Model behavior of solid objects • Voxels • Connected with strong link values [Mazarak99] • Scaled/displaced in any directions [Martins01] • Has unique material properties

  20. Mass-spring models • Tetrahedral elements • Each element equivalent six springs [Smith00] • Elements with same size cause undesirable artifacts [Hirota00] and lead with size adapted [Aoki04]

  21. Finite element methods • Classic • Brittle/Ductile fracture animation [O’Brien99; O’Brien00; O’Brien02] • Simulation determinates cracks initiation and propagation analyzing stress value • High computation time

  22. Finite element methods • Classic • Fluid dynamics model based using O’Brien approach [Yngue00] • An approach using heuristical stress [Iben09] • Replace as few tetrahedral as possible [Wicke10]

  23. Finite element methods • Hybrid • Alternate rigid body and continuous model at the point of impact [Muller01; Molino04]

  24. Finite element methods • Hybrid • Alternate rigid body and continuous model at the point of impact [Muller01; Molino04] • Bi-layered materials • Cracking induced by the material growth/shrinkage [Federl02] • Delaunay triangulation for mesh construction

  25. Meshless methods • Based on particles/point-based representation • Compute spatial derivatives of displacement • Synthetize crack surfaces as triangle meshes [Muller04; Pauly05; Steinemann06]

  26. Other methods • Crack propagation based on multi-layer Cellular Automata [Gobron01] • Crack propagation by systematic stress release of unstable cells

  27. Physically-based methods • Which to choose? • Mass-spring, simple and fast / quality • FEM, accurate simulation / computational cost • Mesh-less, avoid mesh treatment / bounding restrictions • General problems • Computational time vs. quality

  28. Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work

  29. Non-physically based methods

  30. Image-based methods • Information extracted from images • Textured height field pattern [Wang03] • Reproducing input lines from images [Mould05] • Mapping and Bump mapping with real images [Hsien06] →

  31. Procedural methods • Open, flexible and parameterizablesolution • Parallel strips to simulate bark generation [Lefebvre02] • Tools to control the patter by observation [Martinet04] • Mathematic algorithm to cracks in wax painting [Wyvill04]

  32. Procedural methods • Connected voxel method as basis [Taubman04; Valette07] • Combining with mathematical equations for explosion or predefined crack path

  33. Non-physically based methods • Advantages: • Intuitive • User control • Use criterion based… • In patterns extracted from images information • On the observation • Some simplified rules

  34. Non-physically based methods • Problems • Visual quality could be improved • Suitable for interactivity application e.g. video games

  35. Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work

  36. Conclusions • Simulating fracture → a challenging task • Modeling the process: • Plausability → do physical simplifications • Accurate simulation → physical approach • Does not exist one ideal model for all kinds of applications

  37. Conclusions

  38. Problems • Quality simulation results small fragments/dust • Computation time required real-time to min/hours • Limited user control over animations Trade-off between then

  39. Methods validation • Physically-based methods • Compare with experiments on real surfaces • Perception [Valette05; Ramanarayanan07] • Non-physically based methods • From a scientific point of view [Lu07] [Federl02]

  40. Overview • Background • Physically-based methods • Non-physically based methods • Conclusions • Future work

  41. Future work • Reproduce a specific pattern simulation • Example based techniques restricted to given pattern • An open problem • Combination of simulation + synthesis[Bosch11] • Extend → cracks and fractures No trivial

  42. Challenge • Parameters extraction → images/geometry/other • Observation/Statistics • Find simulation parameters of a specific fracture state of the art study • Based on an existing simulation model

  43. Inverse model process caracteristics • Urban environment Building materials Indirected causes Resistents No elastic

  44. Our inverse model process • Not accurate model • Real time solution • Simulation image-guided → promess process

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